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NEAX2400 IPX ISDN Features and Specifications
NDA-24311, Issue 1
Page 173
D Channel Backup - PRI D-152
D-152 D Channel Backup - PRI
General Description
This feature provides a backup D-channel in non-facility associated signaling, by which even if the primary
D-channel encounters link down, etc., the backup D-channel may be active.
Operating Procedure
Manual switch-over is available by:
• designating the required route by means of MAT command (CDBU).
• pull up MB switch on a circuit card of the active D-channel. (Circuit card Make Busy)
• switching on the LB#3 switch on a circuit card of the active D-channel. (Dch handler Make Busy request)
Service Conditions
1. This service may be provided when non-facility associated signaling is employed.
2. The protocol for network interface is AT&T or Nortel.
3. Main and backup D-channels, and all controlled B-channels, must be assigned in the same LP.
4. If the 2DCH circuit card is used, assignment of both main and backup D-channels is not permitted on the
same circuit card.
5. Start/completion of D-channel switch-over displays as a system message.
6. The switch-over status may be displayed from the MAT.
7. Switch-over from the MAT must be done only when both main and backup links are established. (Pulling
up MB switch or switching on the LB#3 switch on a circuit card is not restricted.)
8. Office data for the backup D-channel must not be changed during switch-over.
9. A speech path is kept during and after switch-over.
10. Send/received messages in firmware during a layer 2 failure are cleared.
11. Identification of the active D-channel cannot be determined by the LED on the circuit cards. (It is available
by reading the memory from the MAT command.)
12. Just after the system/LP initialization, the primary D-channel is ACT. However, if the backup
D-channel is established before the primary D-channel is done, backup D-channel is ACT.
13. Timer value of T321 may be determined by system data. Its default value is 30 seconds.
14. Backup timer value may be determined by system data. Its default value is 0 second.
15. This service supports T309. (This is used to set the recovery time from both main and backup D-channels
lost link.)